Why do clutches drag with lever pulled in?

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9/19/2017 8:04 PM
Edited Date/Time: 9/19/2017 8:05 PM

I have owned a few dozen bikes and every one of them drags the clutch a little when the clutch is pulled in. Doesn't matter if the bike is off road, dual sport or road. Doesn't matter how far the clutch pulls. Doesn't matter how old or new the bike is. Every one of them drags the clutch a little when the lever is pulled in. Should be noted I always run dinosaur oil in my trannys.

I am wondering what the deal is. Do clutches a always drag a little due to oil viscosity and rpms creating enough friction even if the clutch plates are separate?

Would synthetic oil slip better to overcome the drag when the clutch is pulled in?

Been thinking to maybe try tranny fluid instead of oil in my dirt bike if it offered more slip with the clutch pulled in and still protected the tranny same as oil. I have heard its OK to run tranny fluid but don't know if this is for only for Sunday rider putt putters or hard ripping riders too. Would running tranny fluid actually help the drag issue? Is tranny fluid really OK to run in a hard driven dirt bike engine?

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9/20/2017 2:14 AM

Every bike i own does not do that. My clutches stop dragging way before the lever hits my fingers. Sounds like you need to adjust your cables

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2009 Kawasaki KX450F
2009 Kawasaki KX250F
2002 Suzuki GSXR 600

9/20/2017 3:29 AM

You can use tranny fluid in a two stroke or in a four stroke honda that has the split trans/crank oil but not a regular four stroke

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9/20/2017 2:59 PM
Edited Date/Time: 9/20/2017 3:07 PM

Acidreamer wrote:

Every bike i own does not do that. My clutches stop dragging way before the lever hits my fingers. Sounds like you need to adjust your cables

Nope. Cables on the past few dozen bikes I have rode were fine and so was the lever pull. I have removed side covers and seen the gap between the plates when the lever is pulled on a few of them out of curiosity. I am not saying there is massive drag. Sometimes its very minimal in the background. Every bike I have ever ridden has it to some extent.

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9/20/2017 3:01 PM
Edited Date/Time: 9/20/2017 3:07 PM

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9/20/2017 3:06 PM

The oil you use in the trans can have an effect on clutch drag. So can notched baskets and worn disk and warped disk. If the clutch basket and plates are in good shape and the clutch actuation parts are good, then I would have a look at the oil you are using.
I don't want to open a can of worms here, but try Shell Rotella T6 as I have seen less clutch drag with it than any other oil.

Paw Paw

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9/20/2017 3:07 PM

rmoto003 wrote:

You can use tranny fluid in a two stroke or in a four stroke honda that has the split trans/crank oil but not a regular four stroke

Hahahahaha! Holy crap I hadn't thought of 4 stroke dirt bikes in the conversation. I only own two strokes. Yah definitely wouldn't put tranny fluid in a 4 stroke.

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9/20/2017 3:21 PM

Paw Paw wrote:

The oil you use in the trans can have an effect on clutch drag. So can notched baskets and worn disk and warped disk. If the clutch basket and plates are in good shape and the clutch actuation parts are good, then I would have a look at the oil you are using.
I don't want to open a can of worms here, but try Shell Rotella T6 as I have seen less clutch drag with it than any other oil.

Paw Paw

Thanks for the info Paw Paw. I was hoping you would way in on this. The worn clutch parts I hadn't thought of. I will look into that. Thinking about it the higher the miles on the bike the more prevalent the drag I notice. I have a KX500 for instance that had the crap kicked out of it by previous owners. Its in good condition overall and runs great since I rebuilt it. Its the bike that drags the most though. The S.O.B. is easiest to start in neutral and often a P.I.T.A. when in gear with the clutch pulled in. Clutch parts looked to be in pretty good condition in the last rebuild but I didn't look to much at them. Its possible the clutch parts may be worn enough to cause a little drag but still are working fine.

I have been running Rotella T 15-40 dinosaur oil. I think I will try the 5-40 T6 synthetic to see if there is a difference.

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9/20/2017 8:24 PM

Clutch on my kx500 sucks. theres a fine line of in or out on the lever. very jumpy and abrupt clutch engagement on that thing.

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9/21/2017 7:32 AM

It will never act like your car's dry clutch no matter what oil or non grooved clutch basket flat discs and plates. All those plates and discs with oil sticking them together, you'll never be able to push it in gear with the clutch pulled. Just part of a wet clutch.
My clutch feels good on the track but when kicking into gear for the first time of the day, it hits pretty hard. I've gotten Bel-Ray 80w gear oil ( I have honda split engine/trans oils ) to reduce this quite a bit, but it's still there.
I think I have grooves in my clutch basket, Only one way to fix that.

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9/21/2017 9:36 AM

mikec265 wrote:

Clutch on my kx500 sucks. theres a fine line of in or out on the lever. very jumpy and abrupt clutch engagement on that thing.

Notched basket, notched inner hub, worn fiber plates (not the fiber face but the drive "ears") are all causes of your issues.

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Tomac and/or Anderson for 2020.....

9/21/2017 12:12 PM
Edited Date/Time: 9/21/2017 12:17 PM

An experiment I once tried:
-My 97 rm250 had a creeping clutch, plus it was weak and acted soft when hot.
-I drilled two TINY holes on the clutch hub where the metal clutch plate spines ride. Every single spline channel, staggering the holes.
-I drilled 4 6mm holes in the main basket, on the back where the gear rides.
-i drilled one 6mm hole on every basket ear, and chamfered all holes.

After this work, I could put my bike into any gear with the engine no running, and the bike would roll as freely as if it were in neutral. Totally fixed my mushy clutch action as well.
The moral to the story is that the plates won't separate cleanly if they're not getting enough oil. I plan o doing this to my new 08 rm250 as well. It totally fixes clutch issues due to not enough lubrication. I did this same fix to my 2000 kx250, and a friends lt250, and it works every time.

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9/21/2017 12:16 PM
Edited Date/Time: 9/21/2017 12:17 PM

Dcope17 wrote:

It will never act like your car's dry clutch no matter what oil or non grooved clutch basket flat discs and plates. All those plates and discs with oil sticking them together, you'll never be able to push it in gear with the clutch pulled. Just part of a wet clutch.
My clutch feels good on the track but when kicking into gear for the first time of the day, it hits pretty hard. I've gotten Bel-Ray 80w gear oil ( I have honda split engine/trans oils ) to reduce this quite a bit, but it's still there.
I think I have grooves in my clutch basket, Only one way to fix that.

Mine always roll freely in gear after i mod the basket for more oil flow. Don't know how that works, but it does. Rolls like it's in neutral.

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